Two inverse problems in photon transport theory: evaluation of a time-dependent source and of a time-dependent cross section

Abstract

In photon transport theory, two types of inverse problems are considered:

(a)

identification of some physical or geometrical quantity (such as a cross section, or a photon source, or the shape of the surface that bounds the host medium), evaluating its dependence on spatial and/or angle variables, under the assumption that photon transport is time independent and starting, for instance, from the knowledge of the exiting photon flux;

(b)

identification of some physical or geometrical quantity that characterizes the host medium, evaluating its dependence on spatial and/or angle variables and on time, under the assumption that photon transport is time dependent and starting, for instance, from the knowledge of the time behaviour of the exiting photon flux.